The Fish Passage Flows portion of the Crossing Input Window is where you enter the Low and High Fish Passage design flows. Profiles will be generated for each of these flows and fish passage conditions will be examined at all flows between them.

• Low and High Passage Flow  - The Low Passage Flow and High Passage Flow define the range of discharges that will be analyzed for fish passage. There are few situations in which fish passage can be maintained during flood flows.  Additionally, it may not be necessary to provide upstream passage conditions during periods of low flow when fish are not attempting to move upstream.  Many state and Federal agencies have guidelines for selecting the low and high passage flows, commonly referred to as fish passage design flows.  See Design Flow Guidelines for a list of current guidelines.

Standard engineering practices dictate that culverts need to be designed to pass water and in many cases wood, bedload and debris at high flows. Commonly the event with a 100-year return period is the maximum design flow. You can use FishXing to model additional flows by using the Flow Calculator, which is located on the Output Summary Window.